The invention relates to a cryoapparatus for freezing and thawing a sample, especially in the cryopreservation of a biological sample, as well as to an associated operating method.
In the known cryopreservation biological samples are frozen while maintaining vitality and subsequently thawed out again as needed while maintaining vitality. Examples of usage for such a cryopreservation are the storage of embryos for stem cell research or the preservation of sperm for a subsequent artificial fertilization. It is important for the maintenance of vitality in cryopreservation that predetermined chronological temperature characteristics are maintained during the freezing as well as during the thawing of the biological sample.
Therefore, so-called automatic freezers are used for the cryopreservation of biological samples that usually use liquid nitrogen with a boiling point of −196° C. as cooling agent and have a cooling space in which the temperature can be adjusted by controlling the supply of the cooling agent in order to achieve the desired chronological temperature characteristics when freezing or thawing biological samples.
During the freezing of biological samples they are inserted into the cooling space of the automatic freezer and subsequently cooled down in accordance with the given chronological temperature characteristics from a starting temperature of a freezing process to a target temperature of the freezing process. After the target temperature of the freezing process has been attained the frozen biological samples are then extracted from the cooling space of the automatic freezer and, e.g., stored in a cryotank.
During the thawing of frozen biological samples they are extracted, e.g., from a cryotank and inserted into the cooling space of the automatic freezer. The temperature of the frozen biological samples is subsequently raised in accordance with predetermined chronological temperature characteristics from a certain starting temperature of a thawing process to a target temperature of the thawing process. After the target temperature of the thawing process has been attained, the thawed sample is extracted from the cooling space of the automatic freezer and further used.
A disadvantage of the previously described known automatic freezer is that the sample is exposed during the insertion into the cooling space and during the extraction from the cooling temperature to undesirable temperature influences that thermally damage the biological sample and can adversely influence the maintenance of vitality.
Furthermore, the previously described known automatic freezer has the disadvantage of an unsatisfactory precision during the adjusting of the given chronological temperature characteristics during freezing and thawing, which is caused by the relatively large volume of the cooling space and the therewith associated problems of regulation technology.
The invention therefore has the task of providing an improved cryoapparatus for freezing and/or thawing a sample and of creating a corresponding operating method.